1. Field of the Invention
This invention relates to moderators and stabilizers of footwear, and more particularly to an improved spring moderator and stabilizer which absorbs, redistributes, and stores energy of localized loads and forces, through elastic deformation, and then returns the energy to the user in useful form as the load is removed. Improved comfort, support, and stability for the foot and lower leg are also provided.
2. Description of the Prior Art
There are numerous articles of footwear in the prior art in which inserts and supporting members are present, principally for the purpose of providing comfortable support to the human foot. For example, U.S. Pat. No. 3,120,712 of 1964 issued to Menken describes a shoe construction which includes a bladder filled to a pressure of about 30 psi. A steel plate overlies the bladder to confine it, and, at a pressure of 30 psi, the plate must support and control a force of 600 pounds and must, accordingly, be extremely rigid and inflexible.
U.S. Pat. No. 2,237,190 of 1941 issued to McLeod describes a shoe incorporating supporting members of springy material which supporting members are corrugated transversely and are thus rigid in a transverse orientation.
U.S. Pat. No. 3,253,355 of 1966 also issued to Menken also describes the use of a stiff plate over an inflatable bladder. The primary purpose of these plates is to contain the fluid pressure within the bladder to provide a flat surface under the foot.
Other patents exist which describe a stiffening or reinforcing plate in the shoe structure, such as arch support devices and the like.
U.S. Pat. No. 4,183,156 discloses a "moderator" described as uniformly distributing relatively high loads associated with fluid-containing chambers in the shoe structure. The moderator is described as being relatively thin, 0.005 to 0.080 of an inch, and is described as being "semi-flexible" to conform to the dynamic contours of the planar surface of the foot. This prior moderator, however, does not perform the function of an energy absorbtion transfer storage and recovery mechanism, but is used solely for foot comfort.
While the above described inserts and supporting members and moderators, as well as others described in the prior art, are said to perform in a manner satisfactory for the purposes therein disclosed, none of the prior art anticipates the basic concepts of this invention: i.e.,
(a) The use of thin high modulas of elasticity, flat or shaped flexural spring elements(s) to absorb otherwise wasted energy from the foot at footstrike, and;
(b) Re-distribute this energy in a time phased relation to the movements of the foot so as to use this otherwise wasted energy to perform other useful functions in the article of footwear, such as:
(1) to cushion and greatly reduce damaging and injury causing shock forces to the foot, leg and body, when walking, running or jumping. PA1 (2) to provide automatic, dynamic improved rear foot and heel support, stability and motion control directly proportioned to the need of the athlete, and/or, PA1 (3) to provide automatic, dynamic improved forefoot control and stability particularly for blocking and stopping movements. PA1 (1) improve overall efficienty, PA1 (2) reduce fatigue, PA1 (3) extend the "float time" for the runner, PA1 (4) to increase the jump height for the basketball player. PA1 (i) increases the energy absorption capability of the entire structure; PA1 (ii) Achieves a better balance between comfort and firmness in the shoe structure; PA1 (iii) improves the "jump height" blocking and stopping characteristics of basketball, tennis and other court shoes; and PA1 (iv) enhances and improves the energy absorption, redistribution, storage and energy return characteristics of those shoes and in-sole structures; PA1 (i) Offers the advantage of use of foam in-sole components which are softer, less dense, and thus of lighter weight, thus retaining softness in the shoe, while providing firmness, as well as the energy return characteristics previously described; PA1 (j) Permits the use of low-pressure inflatable inserts and lower density foams, without experiencing their undesirable "bottoming-out" characteristics, while still retaining the soft cushion feel, but with firmness of support; PA1 (k) Enhances and improves the energy absorption, redistribution, storage and energy return characteristics of the foam or air-gas filled in-sole; and, PA1 (l) Provides a high level of lateral support to the foot, thus either eliminating or supplementing the need for foxing in court shoes and thereby both reducing the weight of the court or all purpose athletic shoe and increasing the level of support and motion control for the entire foot.
(c) To store this energy in a relatively efficient manner within the spring system.
(d) To return this energy to the wearer of the footwear in a time phased, dynamic, and useful manner to:
The subject invention is tailored to work with either, or a combination of fluid/pneumatic and or elastomeric foam support systems.
More specifically, the moderator of this invention provides a variety of unique qualities and functions in combination with elastomeric and/or inflatable elements not heretofore achieved. It is known in the prior art to use foamed inserts or inflatable inserts, normally used as in-soles in foorwear. U.S. Pat. Nos. 4,183,156 and 4,219,945 describe inflatable inserts and combinations thereof with elastomeric materials. These latter patents represent an improvement over the prior art in that the described in-soles absorb localized forces and re-distribute these forces from the localized area, the absorption of forces operating throughout the fluid system of the in-sole. In effect, the fluid system acts as a pneumatic spring. However, they do not combine the elastomeric or inflated elements with a spring-type moderator/stabilizer as in this invention. The moderator of this invention, which is in the nature of a mechanical spring, enhances and improves the energy absorption, redistribution, storage and energy return of the above types of in-soles. Where the in-sole is an all-foam, non-inflatable type of insert, the moderator of the present invention provides similar improved benefits to those of the pressured pneumatic systems.
In general, the moderators of the prior art are either rigid and inflexible and do not conform to the wearer's foot or they are rigid and inflexible and designed to support the foot in a predetermined manner. Alternatively, some are moldably flexible to conform to a desired contour of the foot. In some of the prior art structures the energy of the applied localized load is merely absorbed, and wastefully dissipated, and little, if any, of the absorbed energy is returned in a useful form. Where the energy is merely absorbed, it is usually dissipated in the form of heat, which builds up over a period of time, thereby generating a rise in temperature that may adversely affect the comfort and durability of the footwear.
With footwear to be used in sports related activities, or in severe types of physical activities, the interaction between the foot, footwear and the surface may vary widely, depending upon the nature of the particular activity, the footwear, and the surface. For example, in long distance running, the sequence generally involves heel strike, pronation, and a toe-off "propulsion phase" which is followed by a "float phase." The foot is actually on the ground for only a relatively short period of time. For example, less than 0.30 of a second, and the force loading on the foot may be quite high. In the heel-strike phase, from two to eight times the body weight comes down on the heel in a comparatively short period, and the localized loads may range from about 400 to 1,800 pounds. Where the surface is hard, for example concrete or hardtop, and the footwear is non-compressible, the high loads are absorbed by the heel and transmitted through the related bone structure to the remainder of the body. Thus, from the standpoint of comfort and protection from injury, either a soft running surface or a soft cushioned shoe structure, or a combination thereof is desirable.
However, the toe-off propulsion phase tends to require firmness because of the propulsion mechanism. Here, more firm surface and a less cushioned shoe structure, or a combination thereof, is desirable. For footwear of a given type, the effect may be different for different types of surfaces, e.g., turf, concrete, or hardwood surfaces. Turf is yielding and while it cushions heel strike better than does concrete or hardwood, the yielding nature makes toe-off propulsion more strenuous. Concrete and hardwood favor the dynamics of toe-off propulsion, and hardwood is preferable over concrete because hardwood is somewhat resilient and tends to cushion heel strike. While the almost imperceptable resiliency of hardwood compared to concrete might not seem significant, it is very significant from the standpoint of foot comfort and protection from injury for the athlete. It is primarily for this reason that hardwood rather than much less costly concrete floors are used in most gymnasiums.
From the nature of distance running, it is important that the footwear used be designed to not only give the proper amount and degree of cushioning protection at heel strike, the footwear should also be capable of (a) redistributing and efficiently storing the energy at heel strike (which is composed of both a negative downward and reward force vector) and (b) returning that stored energy to the athlete as a positive propulsive force having both upward and forward vectors. This energy must also be returned to the athlete in a properly time-phased relation to the rhythm of his gait, (i.e., that is in resonance with the articulated pendulum movement of his legs and feet--and the up and down `bouncing ball` movement of his head and torso) so as to enhance and not retard the activity. It should be noted here the importance of proper timing in the return of the stored energy. If the energy returns too rapidly, it could actually detract from the overall efficiency and could cause a runner to run more slowly and with less efficiency. If the energy is returned too slowly, there would be little or no efficiency improvement and the energy would simply be thrown away.
It may appear difficult or impossible to store enough energy within the thin sole of a shoe to significantly improve the efficiency and performance of an athlete, such as a distance runner. However, a recent technological advancement has been made in athletic footwear that has achieved the above goals. It is the Air-Sole.RTM. described in my earlier U.S. Pat. No. 4,183,156. Extensive testing by hundreds of professional athletes reveal efficiency gains when using Air-Sole.RTM. shoes, in the range of 1/2% to as high as 31/2%. Even gains as small as 1/2%, as measured in treadmill/oxygen uptake tests, are physiologically significant and translate into both increased speed and endurance for the athlete. For example, an energy savings of 0.8% is equivalent to roughly one minute and 25 seconds at a three hour marathon race and about one minute at a two-hour and ten minute marathon race. Thus a relatively lightweight, comfortable shoe, which increases efficiency by only a fraction of one percent, represents a significant and beneficial advance in the art.
The nature of the physical activity is an important factor in footwear design and engineering. Long-distance running involves repeating cycles (heel strike, pronation, toe-off propulsion followed by a float phase) with reasonably identical loading patterns. In basketball, for example, the situation is quite different, because the cycle is not repeatable because of the variety of movements in the sport. Also, some of these movements are of such a nature that when the foot or some portion thereof comes into contact with the floor, the loads may be significantly higher and in different directions than those involved in running. For example, a basketball player may come down on the ball or heel of one foot after a high jump thereby causing the localized loads to be significantly in excess of those normally encountered in the heel strike phase of long-distance running. Further, the nature of the sport is such that quick starts, stops and changes of direction take place in a random, non-cyclicle manner. To some extent, the same is true in sports such as soccer or football played on artificial turf or grass, but the surface tends to be more resilient than the hardwood surface. Also, tennis presents the same variety of foot motion, although high jumps are not as frequent. However, the surface is usually very hard.
It is known from U.S. Pat. No. 4,183,156 that particular types of inflatable in-sole structures there described are capable of absorbing localized forces and storing and returning mechanical energy to the foot and leg so as to reduce the "energy of locomotion" required in running, walking and jumping. As described in the above-identified patent, displacement energy is absorbed from the foot by the inflated in-sole as the foot makes contact with the ground, the energy being converted to fluid pressure energy and stored within the inflated in-sole and then is converted back to energy of motion at the end of the stride as the foot leaves the ground. The described in-soles are initially filled with one, or a combination of special, inert, man-made, high molecular weight gases so as to achieve essentially permanent inflation coupled with the unique abilities to automatically compensate (over a period of time) for ambient changes in pressure such that the differential pressure (i.e., the pressure inside the device vs. the ambient pressure outside the device) remains essentially constant for the life of the product. Thus the product could be manufactured at sea level and used in high mountain areas and have the same "feel" and level of support. The reverse would also be true (i.e., manufacture the device at high elevation and then use it at sea level.
While the above-described in-soles have many new, novel and useful features, operate satisfactorily, and include moderators to provide comfort, in some applications it has been necessary to use relatively high inflation pressures and/or relatively high density, heavy weight foams to withstand the relatively large localized loads produced in certain types of activities such as jumping. Further, while those in-soles were effective in absorbing and converting the energy ultimately into energy of locomotion, the maximum use of the available energy was not achieved. More specifically, the redistribution of energy was related to the communicating fluid passages for the air-gas mixture, thus requiring in-sole geometries which tended to be difficult as a practical matter.
One of the advantages of the inflatable in-sole structures was the adiabatic compression of the gas in response to applied loads and the transfer of energy at a relatively high rate approximating the speed of sound, i.e., 1088 feet/second. Energy was also transferred stored throughout the elastomeric or plastic material which formed the fluid containing envelope, but the rate of energy transfer was significantly slower than that through the air-gas mixture. In the case of foam materials, the rate of energy transfer is relatively slow, e.g., about one foot per second or less. The result was that in some instances the dynamics of energy absorption, distribution and return was not properly "tuned" to the wearer's activity. The result was that the available energy was not as optimally utilized as it could have been.
Comfort and shock absorption are important factors by themselves that can increase efficiency and performance of the athlete. It has been shown that the body expends energy simply in absorbing and attenuating the impact and shock loads experienced in running. Further, sore, or even temporarily damaged muscles, ligaments, nerves, etc., do not function as efficiently as normal body elements. Hence the best possible shoe design will optimize the factors of (a) comfort and shock absorption, (b) lightness of weight, (c) efficient energy absorption, redistribution, storage and return, (d) rear foot, arch, and forefoot support and motion control. The Air-Sole.RTM. and variations thereof has achieved a significant degree of optimization of these factors not previously possible in any other footwear. However, there are certain requirements in footwear design where the present embodiment of the Air-Sole.RTM., by itself, is not the best design. Furthermore, the subject of this invention is able to achieve many of the desirable energy absorption, redistribution, storage and return features of the Air-Sole.RTM., without the use of the Air-Sole.RTM., or, it can also be used to enhance the overall performance characteristics of shoes using the Air-Sole.RTM.. The subject invention is particularly valuable (in comparison with the Air-Sole.RTM. by itself) in achieving a unique and highly beneficial degree of dynamic rearfoot, arch and forefoot motion control and support, not presently possible with the Air-Sole.RTM. or any other footwear design. As will be seen in the following discussion, the special geometry and design of the spring moderator absorbs, redistributes, stores and returns energy to the athlete in a manner beneficially different from the Air-Sole.RTM. or any other prior art device.
In view of the foregoing, one of the objects of this invention is to provide an improved moderator which cooperates with the other components of the article of footwear to absorb, redistribute, store and return energy to the user in a far better fashion than can be achieved by the same structure without the moderator of this invention.
Additional specific objects of this invention include:
(a) Achievement of a "banked track" effect between the foot and the running surface proportional to the applied vector forces;
(b) Achievement of improved running efficiency when properly combined with either all foam and/or an air-gas in-sole system;
(c) Improvement of stability at heel strike and toe-off phases of footwear function regardless of whether an air-gas in-sole system is used;
(d) Providing improved and increased support for individuals defined as "pronators";
(e) Cooperating with the heel counter of the footwear to create a dynamic cupping action working in combination with the heel counter to snug the heel counter more firmly around the heel of the foot at moments of severe downward (or combined lateral and downward) impact between the foot and the ground;
(f) Permitting the use of softer foam and/or lower pressure air-gas in-soles to achieve higher levels of comfort and impact/shock absorption and at the same time to tune more precisely the dynamics of the shoe to the athlete and to the activity, for example, running, tennis, basketball, track, soccer, football, etc.;
(g) Absorbing, redistributing and storing the energy of localized loads and forces through elastic deformation of the spring moderator element and then returning the energy to the athlete as the load is removed;
(h) When used with footwear or in-sole constructions of the type described in U.S. Pat. Nos. 4,183,156; 4,219,156; 4,219,945 and 4,271,606 the moderator structure of the present construction